A communication network that provides services to transmit Ethernet (standardized by IEEE 802.3 committee) frames via a pseudo wire in an MPLS (Multi Protocol Label Switching) has been developed, as is disclosed in RFC 3031, RFC 3032, RFC 3985 and IEEE Std 802.3.
To transmit the Ethernet (standardized by IEEE 802.3 committee) frame transparently, an encapsulation of the Ethernet (standardized by IEEE 802.3 committee) frame with a pseudo wire label, a tunnel label and a physical layer is necessary within an MPLS network. According to related arts, a whole Ethernet (standardized by IEEE 802.3 committee) service frame received from a user is encapsulated with the pseudo wire label, and is transmitted by the MPLS network.